This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-029823, filed Feb. 8, 1999, the entire contents of which are incorporated herein by reference.
This invention relates to a display device of an optical apparatus.
A camera is provided as one of optical apparatuses and it is conventionally proposed to use a liquid crystal for a display section in the finder of the camera. Display of an AF target and various modes and display on switching of the angles of a view such as a panorama view and normal view are provided by use of the liquid crystal. As the type of the liquid crystal, positive type LCDs such as a so-called TN (twisted nematic) type LCD (which is hereinafter referred to as a TN-LCD) and guest host LCD (which is hereinafter referred to as a GH-LCD) are conventionally frequently used.
Recently, as is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-165017, it is proposed to use a high polymer dispersion type liquid crystal (which is hereinafter referred to as a PN-LCD) for the finder of the camera. The PN-LCD permits incident light to be scattered or transmitted as it is according to the voltage application state. Since the degree of scattering is high in the PN-LCD when the incident light is scattered, the amount of light which is directly incident on the eye becomes extremely small if it is used for the finder and the light shielding state or dark state can be attained as if light is mechanically shielded. A high contrast finder can be constructed by use of the PN-LCD in comparison with the TN-LCD and GH-LCD.
As the above types of liquid crystals, a negative type liquid crystal in which the light transmitting state is attained when a voltage is applied thereto and the light shielding (diffusion) state is attained when a voltage is not applied thereto and a positive type liquid crystal in which the light shielding (diffusion) state is attained when a voltage is applied thereto and the light transmitting state is attained when a voltage is not applied thereto are both known.
In the above Jpn. Pat. Appln. KOKAI Publication No. 5-165017, the construction of a combination of the TN-LCD and PN-LCD is disclosed, the PN-LCD is used in an image area for displaying a scenery and the TN-LCD is used in an area for displaying various types of information items. The PN-LCD is used as the positive type liquid crystal and no voltage is applied thereto to set the same in the light transmitting state. The TN-LCD is also used as the positive type liquid crystal and displays various information by use of a light transmitting portion to which no voltage is applied and a light shielding portion to which a voltage is applied.
It is also known in the art to display information relating to the range of an image and information relating to photographing by printing or marking-off.
In the above Jpn. Pat. Appln. KOKAI Publication No. 5-165017, in order to display a scenery and various types of information items in the finder, the PN-LCD and TN-LCD are used in combination. With the above construction, it is necessary to provide an electrode which faces the whole portion of the scenery display portion in order to set the whole scenery display portion into the light transmitting state or light shielding state. Further, since various types of information items are displayed by use of the light shielding portions to which a voltage is applied, it is necessary to provide electrodes in positions facing the various types of information items, thereby making the construction complicated. If an index is made by use of the positive type LCD, it is difficult to integrally shield light on the index and the upper and lower areas thereof at the time of panorama display.
A method for displaying information relating to the range of an image and information relating to photographing by printing or marking-off has a problem that the number of steps at the manufacturing time is increased and a glass plate exclusively used for marking-off is required.
Accordingly, an object of this invention is to provide a display device of an optical apparatus which is simple in construction and can display information relating to the range of an image and photographing by use of a negative type liquid crystal without using a display method by printing or marking-off.
In order to attain the above object, a camera according to a first aspect of this invention comprises a finder device; a liquid crystal element arranged in the finder device and having an image area and at least one of an index area indicating an image range and an index area indicating information relating to photographing; and a control circuit for switching modes between a first mode in which the image area is set into a light transmitting state and a second mode in which the image area is set into a light shielding state according to a voltage applied to the liquid crystal element; wherein the index areas always provide index display irrespective of application of the voltage to the liquid crystal element.
Further, a camera according to a second aspect of this invention comprises a finder device; and a negative type liquid crystal element arranged in the finder device, for forming an index in the finder device by use of a combination of a light transmitting portion which is changed from a light shielding state to a light transmitting state when a voltage is applied thereto and a light non-transmitting portion which is set in the light shielding state irrespective of application of the voltage.
A finder device according to a third aspect of this invention comprises a negative type liquid crystal element having a light transmitting area which is changed from a light shielding state to a light transmitting state when a voltage is applied thereto and a light non-transmitting area which is set in the light shielding state irrespective of application of the voltage, for forming an index by use of a combination of the light transmitting area and the light non-transmitting area; and a control circuit for controlling the voltage application to the light transmitting area of the negative type liquid crystal element.
A camera capable of switching image sizes according to a fourth aspect of this invention comprises a finder device; and a negative type liquid crystal element arranged in the finder device and having a plurality of light transmitting areas each of which is changed from a light shielding state to a light transmitting state when a voltage is applied thereto and a light non-transmitting area which is formed between the plurality of light transmitting areas and set in the light shielding state irrespective of application of the voltage; wherein the light non-transmitting area is used as an index indicating the image size.
A camera capable of switching image sizes according to a fifth aspect of this invention comprises a finder device; and a negative type liquid crystal element arranged in the finder device and having two facing surfaces including electrode areas each having an electrode; wherein the electrode area provided on at least one of the two facing surfaces has a non-electrode area used as an index for indicating the image size in a portion of the electrode area.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.